Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

An electric power generation device equipped with an apparatus which
vibrates and generates heat includes a thermoelectric power generation
module and a piezoelectric power generation module which are formed
integrally. The thermoelectric power generation module has a first
surface combining thermally and mechanically with the apparatus's outer
surface and a second surface opposite to the first surface, and generates
electric power from temperature differences between the first surface and
the second surface caused by the apparatus's generating heat. The
piezoelectric power generation module has a fixed end combining
mechanically with the apparatus's outer surface and a movable end
opposite to the fixed end, and generates electric power from displacement
of the movable end to the fixed end caused by the apparatus's vibrating.

Claims:

1. An electric power generation device equipped with an apparatus which
vibrates and generates heat comprising: a thermoelectric power generation
module which has a first surface combining thermally and mechanically
with the apparatus's outer surface and a second surface opposite to the
first surface, and which generates electric power from temperature
differences between the first surface and the second surface caused by
the apparatus's generating heat; and a piezoelectric power generation
module which has a fixed end combining mechanically with the apparatus's
outer surface and a movable end opposite to the fixed end, and which
generates electric power from displacement of the movable end to the
fixed end caused by the apparatus's vibrating; wherein the thermoelectric
power generation module and the piezoelectric power generation module are
formed integrally.

2. An electric power generation device as set forth in claim 1, wherein
the piezoelectric power generation module is formed over the second
surface of the thermoelectric power generation module, and combines
mechanically with the apparatus's outer surface via the thermoelectric
power generation module.

3. An electric power generation device as set forth in claim 2, wherein:
the piezoelectric power generation module includes radiation fins each of
which has a combination end combining thermally and mechanically with the
second surface of the thermoelectric power generation module and a open
end opposite to the combination end; each of the radiation fins includes:
an inside conductive film deposited at an angle intersecting a plane
parallel to the second surface of the thermoelectric power generation
module, a pair of piezoelectric material plates surrounding the inside
conductive film, and an outside conductive film surrounding the pairing
piezoelectric material plates; and the combination ends of the radiation
fins constitute the fixed end of the piezoelectric power generation
module, and the open ends of the radiation fins constitute the movable
end of the piezoelectric power generation module.

4. An electric power generation device as set forth in claim 3, further
comprising a seat which is deposited between the thermoelectric power
generation module and the piezoelectric power generation module, and
which combines thermally and mechanically with the thermoelectric power
generation module, Wherein: the radiation fins are fixed to the seat at
the combination ends; the outside conductive films of the radiation fins
cover continuously areas extending from the surfaces of the pairing
piezoelectric material plates to the surface of the seat.

5. An electric power generation device as set forth in claim 3, wherein
the pairing piezoelectric material plates have residual polarizations
which are oriented to the same direction in the thickness direction.

6. An electric power generation device as set forth in claim 2, wherein:
the piezoelectric power generation module includes piezoelectric elements
each of which has a piezoelectric material plate and an outside
conductive film surrounding the piezoelectric material plate; the
piezoelectric elements are arranged along the in-plane direction of the
second surface of the thermoelectric power generation module with gaps,
one ends of the piezoelectric elements combining mechanically with the
thermoelectric power generation module and constituting the fixed end of
the piezoelectric power generation module, the other ends constituting
the movable end; the thermoelectric power generation module includes a
thermoelectric element which has thermoelectric material layers and
insulating layers formed of piezoelectric materials, the thermoelectric
material layers and the insulating layers being laminated alternately
along the in-plane direction of the apparatus's outer surface, one side
surface of the thermoelectric element constituting the first surface of
the thermoelectric power generation module, the other side surface
constituting the second surface; and the insulating layers of the
thermoelectric element extend to the piezoelectric power generation
module over the second surface of the thermoelectric power generation
module, and constitute the piezoelectric material plates of the
piezoelectric elements.

7. An electric power generation device as set forth in claim 6, wherein:
the thermoelectric material layers of the thermoelectric element include
p-type thermoelectric layers having p-type conductivity and n-type
thermoelectric layers having n-type conductivity which are arranged
alternately and sandwich the insulating layers; and the gaps defined by
the piezoelectric elements are deposited over the p-type thermoelectric
layers and the n-type thermoelectric layers.

8. An electric power generation device as set forth in claim 6, wherein
each of the piezoelectric elements includes an inside conductive film
embedded in and surrounded by the piezoelectric material plate, and
constitutes a bimorph type piezoelectric element.

9. An electric power generation device as set forth in claim 8, wherein
the outside conductive film has a larger thickness than that of the
inside conductive film, and function also as a heat transfer layer for
the thermoelectric material layer.

10. An electric power generation device as set forth in claim 6, further
comprising a weight which is connected to the other ends of the
piezoelectric elements, with flexible adhesive in between.

11. An electric power generation device as set forth in claim 1, wherein:
the first surface of the thermoelectric power generation module and the
fixed end of the piezoelectric power generation module are formed
integrally; and the second surface of the thermoelectric power generation
module and the movable end of the piezoelectric power generation module
are formed integrally.

12. An electric power generation device as set forth in claim 11,
wherein: the thermoelectric power generation module includes a
thermoelectric element which has one end face near the apparatus's outer
surface constituting the first surface of the thermoelectric power
generation module and the other end face far the apparatus's outer
surface constituting the second surface; the thermoelectric element
includes: a pair of thermoelectric material layers, one of the pairing
thermoelectric material layers which is formed of a p-type thermoelectric
layer having p-type conductivity, the other which is formed of a n-type
thermoelectric layer having n-type conductivity, the pairing
thermoelectric material layers being arranged along the in-plane
direction of the apparatus's outer surface, and a conductive member
connecting electrically the p-type thermoelectric layer and the n-type
thermoelectric layer to each other at the other end face; the
piezoelectric power generation module includes a piezoelectric element
which has one end near the apparatus's outer surface constituting the
fixed end of the piezoelectric power generation module and the other end
far the apparatus's outer surface constituting the movable end; the
piezoelectric element includes: an inside conductive film deposited at an
angle intersecting a plane parallel to the apparatus's outer surface, a
pair of piezoelectric material plates surrounding the inside conductive
film, and a pair of outside conductive films surrounding the pairing
piezoelectric material plates; and the pair of outside conductive films
of the piezoelectric element constitutes the pair of thermoelectric
material layers of the thermoelectric element.

13. An electric power generation device as set forth in claim 11,
wherein: the thermoelectric power generation module includes:
thermoelectric elements each of which has one end face near the
apparatus's outer surface constituting the first surface of the
thermoelectric power generation module and the other end face far the
apparatus's outer surface constituting the second surface, and first
conductive members connecting electrically the thermoelectric elements to
each other; each of the thermoelectric elements includes: a pair of
thermoelectric material layers, one of the pairing thermoelectric
material layers which is formed of a p-type thermoelectric layer having
p-type conductivity, the other which is formed of a n-type thermoelectric
layer having n-type conductivity, the pairing thermoelectric material
layers being arranged along the in-plane direction of the apparatus's
outer surface, and a second conductive member connecting electrically the
p-type thermoelectric layer and the n-type thermoelectric layer to each
other at the other end face; the mutually adjacent thermoelectric
elements are deposited so that the p-type thermoelectric layer and the
n-type thermoelectric layer face to each other; each of the first
conductive members connects electrically the facing p-type thermoelectric
layer and n-type thermoelectric layer to each other at the one end face;
the piezoelectric power generation module includes piezoelectric elements
each of which has one end near the apparatus's outer surface constituting
the fixed end of the piezoelectric power generation module and the other
end far the apparatus's outer surface constituting the movable end, the
piezoelectric elements being arranged along the in-plane direction of the
apparatus's outer surface with gaps; each of the piezoelectric elements
includes: an inside conductive film deposited at an angle intersecting a
plane parallel to the apparatus's outer surface, a pair of piezoelectric
material plates surrounding the inside conductive film, and a pair of
outside conductive films surrounding the pairing piezoelectric material
plates; and the pairs of outside conductive films of the piezoelectric
elements constitute the pairs of thermoelectric material layers of the
thermoelectric elements.

14. An electric power generation device as set forth in claim 13, further
comprising: weights mounted on each of the piezoelectric elements at the
other end; and spacers connecting mechanically the mutually adjacent
weights to each other, fixing relative positions between central points
of the mutually adjacent weights, and allowing relative attitude changes
of the mutually adjacent weights.

15. An electric power generation device as set forth in claim 14, wherein
the weights include heat exchange fins.

16. An electric power generation device as set forth in claim 13, further
comprising a weight mounted on the piezoelectric elements at the other
ends with adhesive, wherein the adhesive has flexibility to allow changes
in the attitude of the other ends of the piezoelectric elements with
respect to the attitude of the weight.

17. An electric power generation device as set forth in claim 16, wherein
the weight includes heat exchange fins.

18. An electric power generation method comprising: generating
thermoelectric power by equipping a thermoelectric conversion material
which is provided with radiation fins with an apparatus which vibrates
and generates heat; and generating piezoelectric power from deformation
of a piezoelectric conversion material which forms a portion of the
radiation fins, the deformation being caused by vibrations of the
apparatus.

19. An electric power generation device manufacturing method comprising:
forming a laminated structure which includes green sheets formed of
piezoelectric ceramics, conductive layers, organic resin layers, and
support layers, wherein: the green sheets are disposed at intervals, in a
first region pertaining to the in-plane direction of the green sheets,
the conductive layers are disposed on both surfaces of each of the green
sheets, and the organic resin layers are inserted between the conductive
layers, in a second region different from the first region, the support
layers are deposited between the green sheets; and calcining the
laminated structure to form piezoelectric material plates from the green
sheets, and to remove the organic resin layers and form gaps between the
piezoelectric material plates in the first region, with remaining the
support layers in the second region.

20. An electric power generation device manufacturing method as set forth
in claim 19, which furthermore comprises forming thermoelectric elements
that include the support layers, wherein the support layers being made of
a thermoelectric material.

Description:

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation application of an International
Patent application PCT/JP2010/004605, filed in Japan on Jul. 15, 2010,
the whole contents of which are incorporated herein by reference.

BACKGROUND

[0002] 1. Field

[0003] The embodiments discussed herein are related to an electric power
generation device using thermoelectric conversion and piezoelectric
conversion, to a pertinent electric power generation method, and to a
pertinent electric power generation device manufacturing method.

[0004] 2. Related Art

[0005] Efforts have been made to promote the development of a sensor
network containing sensor modules that integrate sensors, a data
processing function, and a radio communication function provided on a
network. It is desired that such sensor modules perform self-generation
without using a battery. For self-generation, studies are being made of
electric power generation methods which use on-site environments and
serve to provide miniaturized devices, such as methods using solar cell
power generation, thermoelectric power generation, and piezoelectric
power generation. Miniaturization of electric power generation devices
are desired also for securing wide application ranges.

[0006] A unimorph type piezoelectric element is known which contains a
piezoelectric capacitor including a lower electrode made of Pt or the
like, a piezoelectric layer made of PZT or the like, and an upper
electrode made of Al or the like and formed on the upper surface of a
cantilever structure comprising a silicon layer or the like. A weight is
connected to the movable end of the cantilever.

[0007] The electric power generated by a piezoelectric element is too
small in quantity to be used as a power supply. Therefore, in many cases,
a plurality of piezoelectric elements are connected in parallel to obtain
practicable electric power. It is not easy for a large number of
cantilever-structured unimorph type piezoelectric elements to be combined
in a compact device.

[0008] A configuration is disclosed in which a plurality of piezoelectric
elements consisting of piezoelectric plates formed on metal plates are
laminated on a common support structure and supported in the peripheral
portion, with weights applied to the central portions of the
piezoelectric elements from a common weight applying means (e.g., Patent
Document 1). This configuration is intended to use weights repeatedly
applied by traffic of automobiles and railroad trains and accordingly has
a structure with high mechanical strength.

[0009] The output voltage of a thermoelectric element containing a pair of
thermoelectric material articles connected together depends on the
temperature difference, but in many cases, the voltage is low, making it
necessary to connect a large number of pairs of thermoelectric elements
in series in order to obtain a practicable voltage. For example, an
output voltage is increased by using a large number of n-type
configurations, each consisting of a pair of a p-type semiconductor and
an n-type semiconductor arranged adjacently to each other and
electrically connected together at one end, that are disposed between a
high temperature side and a low temperature side and connected in series.
Thermoelectric elements require no movable portion and can be integrated
easily. However, it is necessary to insulate adjacent thermoelectric
members from one another.

[0010] A configuration is proposed wherein, in a structure in which p-type
semiconductors and n-type semiconductors are laminated, insulating layers
are interposed on lamination interfaces that are other than p-n
connections (e.g., Patent Document 2). All layers are laminated in a
green state, and are integrally calcined.

[0011] There is a proposal for a thermoelectric conversion module composed
of a plurality of thermoelectric elements connected in series, with the
spaces between thermoelectric elements filled with insulating resin to
fix the thermoelectric elements to each other (e.g., Patent Document 3).

[0012] There is another proposal for a thermal displacement conversion
device that combines a thermoelectric power generation device and a
piezoelectric actuator (e.g., Patent Document 4). A thermoelectric
element formed of a thermoelectric conversion material generates a
voltage which is proportional to an applied temperature, and this voltage
causes displacement of the piezoelectric actuator.

[0020] There is a call for a technology to allow thermal, vibrational, or
other energy which would be otherwise discarded to be recovered as
electrical energy. Development of small size electric power generation
devices is also desired.

[0021] According to one aspect of the present invention, an electric power
generation device equipped with an apparatus which vibrates and generates
heat includes:

[0022] a thermoelectric power generation module which has a first surface
combining thermally and mechanically with the apparatus's outer surface
and a second surface opposite to the first surface, and which generates
electric power from temperature differences between the first surface and
the second surface caused by the apparatus's generating heat; and

[0023] a piezoelectric power generation module which has a fixed end
combining mechanically with the apparatus's outer surface and a movable
end opposite to the fixed end, and which generates electric power from
displacement of the movable end to the fixed end caused by the
apparatus's vibrating;

[0024] wherein the thermoelectric power generation module and the
piezoelectric power generation module are formed integrally.

[0025] According to another aspect of the present invention, an electric
power generation method includes:

[0026] generating thermoelectric power by equipping a thermoelectric
conversion material which is provided with radiation fins with an
apparatus which vibrates and generates heat; and

[0027] generating piezoelectric power from deformation of a piezoelectric
conversion material which forms a portion of the radiation fins, the
deformation being caused by vibrations of the apparatus.

[0028] According to still another aspect of the present invention, an
electric power generation device manufacturing method includes:

[0029] forming a laminated structure which includes green sheets formed of
piezoelectric ceramics, conductive layers, organic resin layers, and
support layers,

[0030] wherein:

[0031] the green sheets are disposed at intervals,

[0032] in a first region pertaining to the in-plane direction of the green
sheets, the conductive layers are disposed on both surfaces of each of
the green sheets, and the organic resin layers are inserted between the
conductive layers,

[0033] in a second region different from the first region, the support
layers are deposited between the green sheets; and

[0034] calcining the laminated structure to form piezoelectric material
plates from the green sheets, and to remove the organic resin layers and
form gaps between the piezoelectric material plates with remaining the
support layers.

[0035] The object and advantages of the invention will be realized and
attained by means of the elements and combinations particularly pointed
out in the claims.

[0036] It is to be understood that both the foregoing general description
and the following detailed description are exemplary and explanatory and
are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 is a cross-sectional view of an electric power generation
device based on Embodiment 1.

[0038] FIG. 2 is a diagram illustrating bent states of polarization.

[0039]FIG. 3A to FIG. 3D are perspective views of a fin in intermediate
stages of manufacturing an electric power generation device based on
Embodiment 1.

[0040]FIG. 3E to FIG. 3H are cross-sectional views of a piezoelectric
generation section in intermediate stages of manufacturing the electric
power generation device based on Embodiment 1.

[0041]FIG. 3I to FIG. 3J are cross-sectional views of a thermoelectric
generation section in intermediate stages of manufacturing the electric
power generation device based on Embodiment 1.

[0042]FIG. 4A is a schematic cross-sectional view of a thermoelectric
generation element. FIG. 4B is a schematic cross-sectional view
illustrating a configuration of a piezoelectric-thermoelectric generation
device based on Embodiment 2. FIG. 4C is a schematic cross-sectional view
illustrating another configuration of a piezoelectric-thermoelectric
generation device based on Embodiment 2.

[0043]FIG. 5A to FIG. 5M are cross-sectional views and top views
illustrating main steps in the method of manufacturing a bimorph type
piezoelectric-thermoelectric generation device based on Embodiment 2.

[0044]FIG. 6A is a cross-sectional view of an electric power generation
device based on Embodiment 3. FIG. 6B is the electric power generation
device in a bent state.

[0045]FIG. 7A is a side view of an electric power generation device based
on Embodiment 3. FIG. 7B is a cross-sectional view of FIG. 7A through the
dashed-dotted line 7B-7B.

[0046]FIG. 8 is a cross-sectional view of an electric power generation
device based on Embodiment 4.

[0047]FIG. 9 is an equivalent circuit diagram of the electric power
generation device based on Embodiment 4.

[0048] FIG. 10 is a schematic cross-sectional view of the electric power
generation device based on Embodiment 4 at a time when the device is
bent.

[0049] FIG. 11 is a cross-sectional view of an electric power generation
device based on a variant example of Embodiment 4.

[0050] FIG. 12 is a schematic cross-sectional view of the electric power
generation device based on the variant example of Embodiment 4 at a time
when the device is bent.

[0051] FIG. 13A to FIG. 13O are cross-sectional views of the electric
power generation device based on Embodiment 4 in intermediate stages of
manufacturing the device.

[0052] FIG. 13P is a cross-sectional view of FIG. 13O through the
dashed-dotted line 13P-13P.

[0053] FIG. 14A is a cross-sectional view of an electric power generation
device based on Embodiment 5 in an intermediate stage of manufacturing
the device. FIG. 14B is a cross-sectional view of FIG. 14A through the
dashed-dotted line 14B-14B. FIG. 14C to FIG. 14E are cross-sectional
views of the electric power generation device based on Embodiment 5 in
intermediate stages of manufacturing the device. FIG. 14F is a
cross-sectional view of FIG. 14E through the dashed-dotted line 14F-14F.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment 1

[0054] FIG. 1 illustrates a cross-sectional view of an electric power
generation device based on Embodiment 1. The electric power generation
device based on Embodiment 1 includes a thermoelectric power generation
section (thermoelectric power generation module) 10 and a piezoelectric
power generation section (piezoelectric power generation module) 30.

[0055] Hereinafter, an explanation will be made of the configuration of
the thermoelectric power generation section 10. A plurality of p-type
thermoelectric conversion members 18 and n-type thermoelectric conversion
members 19 are held between a first substrate 11 and a second substrate
12. Each of the p-type thermoelectric conversion members 18 and each of
the n-type thermoelectric conversion members 19 are connected to the
first substrate 11 through first conductive patterns 12 and are connected
to the second substrate 15 through second conductive patterns 16. The
plurality of p-type thermoelectric conversion members 18 and n-type
thermoelectric conversion members 19 are alternately connected in series
by first connective patterns 12 and second connective patterns 16. A
power takeoff terminal 20 is connected to both ends of this series
circuit.

[0056] An insulating material with excellent thermal conductivity, such as
alumina, is used for the first substrate 11 and the second substrate 15.
Silver, for example, is used for the first conductive pattern 12 and the
second conductive pattern 16. Ca3Co4O.sub.9 and
Ca0.9La0.1MnO3, for example, are used for the p-type
thermoelectric conversion members 18 and the n-type thermoelectric
conversion members 19, respectively. As an example, the shape of each of
the p-type thermoelectric conversion members 18 and each of the n-type
thermoelectric conversion members 19 is a cube with a side length of 2
mm.

[0057] The configuration of this thermoelectric power generation section
10 is a so-called n-type structure wherein p-type thermoelectric
conversion members and n-type thermoelectric conversion members are
connected in series. A thermoelectric module with another structure may
be adopted for the thermoelectric power generation section 10.

[0058] In the next place, an explanation will be made of the configuration
of the piezoelectric power generation section 30. A seat 31 is joined to
the second substrate 15 of the thermoelectric power generation section
10, and is thermally connected to the second substrate 15. A material
with excellent thermal conductivity, such as aluminum, is used for the
seat 31. On the surface of the seat 31, there are formed a plurality of
grooves 32 which are disposed in parallel to one another. One end of each
of heat exchange fins 40 is inserted into one of the grooves 32, and is
fixed thereto. A plurality of fins 40 are arranged in parallel to one
another.

[0059] Each of the fins 40 includes an inside conductive film 41, two
thermoelectric material plates 42, two base conductive films 43, and two
outside conductive films 44. The inside conductive film 41 is held
between the two thermoelectric material plates 42. At the edge which is
fixed to the seat 31, the thermoelectric material plates 42 are in direct
contact with each other, and the inside conductive film 41 is not exposed
to the end face. That is, the inside conductive film 41 is electrically
insulated from the seat 31. A laminated structure which includes the
inside conductive film 41 and the two thermoelectric material plates 42,
is held between the outside conductive films 44. Base conductive films 43
are disposed between the thermoelectric material plates 42 and the
outside conductive films 44.

[0060] The outside conductive films 44 continuously cover areas extending
from the surfaces of the thermoelectric material plates 42 to the surface
of the seat 31. Therefore, a pair of outside conductive films 44, between
which is held the laminated structure that includes the inside conductive
film 41 and the two thermoelectric material plates 42, are electrically
short-circuited through the seat 31. Furthermore, the outside conductive
films 44 are thermally connected to the second substrate 15 through the
seat 31. The heat of the second substrate 15 is transferred to the
outside conductive films 44 via the seat 31, and is further radiated to
the surrounding space.

[0061] Platinum (Pt), for example, is used for the inside conductive film
41 and the base conductive films 43. A piezoelectric material such as
lead zirconate titanate (PZT) or lead lanthanum zirconate titanate (PLZT)
is used for the thermoelectric material plates 42. In this regard, it is
preferable to use an oxide piezoelectric material as a piezoelectric
material. Polarization treatment is performed on the thermoelectric
material plates 42 so that spontaneous polarizations will be oriented in
the thickness direction. Thermoelectric material plates 42 of a plurality
of fins 40, which are arranged in parallel, are disposed in such an
attitude that the residual polarizations of the thermoelectric material
plates 42 will be oriented in the same direction.

[0062] The inside conductive films 41 are exposed to the end faces of the
tips (the edges opposite to the edges which are fixed to the seat 31) of
the fins 40. A lead cable 34 is connected to the inside conductive films
41, which are exposed to the end faces. The lead cable 34 and the outside
conductive films 44 are connected to a power takeoff terminal 35.

[0063] Hereinafter, an explanation will be made of the operation of the
electric power generation device based on Embodiment 1. The first
substrate 11 is mounted on a device which generates heat and vibrations,
such as an internal combustion engine. The temperature of the first
substrate 11 rises due to the heat transferred from the device which
generates heat and vibrations. The heat which is transferred to the
second substrate 15 is radiated to the outside via the heat exchange fins
40. Due to the above, temperature differences occur between both ends of
each of the p-type thermoelectric conversion members 18 and each of the
n-type thermoelectric conversion members 19. Due to these temperature
differences, a voltage is generated in the terminal 20, and is taken out
as electric power.

[0064] The fins 40 vibrate due to the vibrations of the device which
generates heat and vibrations. Fins 40 undergo bending vibrations in a
way that the edges fixed to the seat 31 serve as fixed ends and that the
opposite edges serves as free ends. Due to these bending vibrations,
strains are generated in the thermoelectric material plates 42, and
potential differences occur between the inside conductive films 41 and
the outside conductive films 44. These potential differences are taken
out, as electric power, to the outside through the terminal 35.

[0065] FIG. 2 illustrates the polarization states of piezoelectric
material plates 42 and the states of electric charges generated. Residual
polarizations P0 which are in the same direction remain in two
piezoelectric material plates 42, between which an inside conductive film
41 is held. If this fin is bent, an in-plane tensile stress acts on the
piezoelectric material plate 42 which is on the outside of bending, and a
compressive stress acts on the piezoelectric material plate 42 which is
on the inside. Due to these stresses, electric charges are generated on
the surface of each of the piezoelectric material plates 42. The electric
charges generated on the convex side surfaces of the two bent
piezoelectric material plates 42 have mutually reverse polarities. The
electric charges generated on the concave side surfaces also have
mutually reverse polarities. Consequently, the electric charges generated
on the surface on the side of the inside conductive film 41 also have the
same polarity, and the electric charges generated on the surfaces on the
side of the outside conductive films 44 also have the same polarity. Due
to these electric charges, an electromotive force is generated between
the inside conductive film 41 and the outside conductive films 44.

[0066] In the next place, by making reference to FIG. 3A to FIG. 3J, an
explanation will be made of a method of manufacturing the electric power
generation device based on Embodiment 1.

[0067] As illustrated in FIG. 3A, a PZT-based ceramic green sheet 42a is
made ready. The thickness of the green sheet 42a is 50-70 μm, for
example. Platinum (Pt) paste is printed on the surface of the green sheet
42a, resulting in a Pt paste film 41a being formed. An exposed portion
with no Pt paste printed is secured in that portion of the green sheet
42a which abuts an edge (a region extending from the edge to a position
slightly inward thereof).

[0068] As illustrated in FIG. 3B, another green sheet 42b is placed on top
of the Pt paste film 41a. The green sheet 42a and the green sheet 42b are
brought into direct contact with each other in the exposed portion to
which no Pt paste is applied. This three-layer structure is degreased at
500° C., and is subsequently calcined at 1,200° C.

[0069] As illustrated in FIG. 3C, due to calcination, there are obtained
an inside conductive film 41 formed of Pt, and piezoelectric plates 42 on
both sides thereof. Pt past is printed on the outer surfaces of the
piezoelectric plates 42, resulting in Pt paste films being formed. These
Pt paste films are calcined at 1,200° C., with the result that
base conductive films 43 formed of Pt are obtained.

[0070] As illustrated in FIG. 3D, polarization treatment is applied by
imposing an alternating current voltage between the base conductive films
43. Due to the above, residual polarizations occur in the piezoelectric
material plates 42. The laminated body illustrated in FIG. 3D is cut off
to a predetermined size.

[0071] As illustrated in FIG. 3E, that edge of each of the laminated
bodies illustrated in FIG. 3D to which an inside conductive film 41 is
not exposed, is inserted into one of the grooves 32 formed in the seat
31.

[0072] As illustrated in FIG. 3F, the edges to which inside conductive
films 41 are not exposed, are covered with mask films 33 made of resist
or the like.

[0073] As illustrated in FIG. 3G, outside conductive films 44 are formed
by applying aluminum plating to the surfaces of the base conductive films
43 and the seat 31. Due to the above, the piezoelectric material plates
42 are fixed to the seat 31 at one end of each of the piezoelectric
material plates 42.

[0074] As illustrated in FIG. 3H, the mask films 33 (FIG. 3G) are removed.
Due to the above, the inside conductive films 41 are exposed to the end
faces at the tips.

[0075] As illustrated in FIG. 3I, first conductive patterns 12 are formed
on the surface of a first substrate 11, and second conductive patterns 16
are formed on the surface of a second substrate 15. Using an electrically
conductive adhesive such as Ag paste, p-type thermoelectric conversion
members 18 and n-type thermoelectric conversion members 19 are bonded to
the first conductive patterns 12. The second substrate 15 is placed on
top of the p-type thermoelectric conversion members 18 and the n-type
thermoelectric conversion members 19. Using an electrically conductive
adhesive such as Ag paste, the p-type thermoelectric conversion members
18 and the n-type thermoelectric conversion members 19 are bonded to the
second conductive patterns 16.

[0076] FIG. 3J illustrates a plane cross-sectional view of FIG. 3I through
the dashed-dotted line 3J-3J. The p-type thermoelectric conversion
members 18 and the n-type thermoelectric conversion members 19 are
disposed matrix-wise on the first substrate 11. The p-type thermoelectric
conversion members 18 and the n-type thermoelectric conversion members 19
are alternately arranged in both the row direction and the column
direction. When sequential numbers are assigned, starting at 1, to
series-connected p-type thermoelectric conversion members 18 and n-type
thermoelectric conversion members 19 in order of connection, then the
first conductive patterns 12 connects the 2i-th n-type thermoelectric
conversion members 19 to the (2i+1)-th p-type thermoelectric conversion
members 18, where i is a positive integer. In this regard, the second
conductive patterns 16 connects the (2i-1)-th p-type thermoelectric
conversion members 18 to the 2i-th n-type thermoelectric conversion
members 19.

[0077] As illustrated in FIG. 1, the seat 31 is bonded to the second
substrate 15 using electrically conductive adhesive. By means of wire
bonding, the lead cable 34 is connected to the inside conductive films
41, which are exposed to the end faces of the fins 40.

[0078] In the electrical power generation device based on Embodiment 1,
heat is radiated through the outside conductive films 44 of the fins 40.
Thus the outside conductive films 44, which acts as electrodes on one
side of the piezoelectric power generation section 30, serves also as
heat radiating fins for the thermoelectric power generation section 10.

[0079] If electrodes are formed on both surfaces of a piezoelectric
material plate, a piezoelectric-effect-caused potential difference occurs
between the electrode on one surface and the electrode on the other
surface. Consequently, it is impossible to make the two electrodes
equipotential. In this structure, it is impossible to bring the two
electrodes into contact with a conductive seat. In Embodiment 1,
equipotential outside conductive films 44 cover both surfaces of each of
the fins 40. Therefore, it is possible to bring the outside conductive
films 44 into contact with the conductive seat. Due to the above, it is
possible to increase the heat transfer efficiency from the thermoelectric
section 10 to the outside conductive films 44.

[0080] In Embodiment 1 mentioned above, it is preferable to design the
shape and the size of the fins 40 so that the bending vibrations of the
fins 40 will resonate with the vibrations of the device on which the
Embodiment 1 is mounted.

[0081] In Embodiment 1 mentioned above, it is possible to increase the
electric power generation efficiency by using thermoelectric power
generation and piezoelectric power generation in combination with each
other.

Embodiment 2

[0082] As illustrated in FIG. 4A, p-type semiconductor layers (p-type
thermoelectric material layers) 51 and n-type semiconductor layers
(n-type thermoelectric material layers) 52 are laminated alternately with
insulating layers 53 therebetween, resulting in a required electrical
connection 54 being formed, with the consequence that a thermoelectric
power generation section (thermoelectric power generation module) TG is
formed. For example, in FIG. 4A, if the upper side of the thermoelectric
power generation section TG is used as a high temperature side, and if
the lower side thereof is used as a low temperature side, a carrier is
transported from the high temperature upper side to the low temperature
lower side. If the p-type semiconductor layers 51 and n-type
semiconductor layers 52 are connected together in the high temperature
portion, then the low temperature portions of the p-type semiconductor
layers 51 are positively charged, and the low temperature portions of the
n-type semiconductor layers 52 are negatively charged. If a plurality of
pairs (three pairs in FIG. 4A) of thermoelectric elements are connected
in series in the low temperature portion, and are connected between
output terminals, then a voltage equal to the sum of the output voltages
of all thermoelectric elements is generated. In this regard, pairs of
p-type semiconductor layers 51 and n-type semiconductor layers 52 do not
need to be used as basic configurations of thermoelectric elements. For
example, measures may be taken such as providing output terminals in the
high temperature portion and the low temperature portion.

[0083] Various kinds of materials such as a heavy metal like Bi--Te/PbTe,
a silicide like FeSi/MgSi, or an oxide like CaCoO/CaMnO can be used as
semiconductor materials (thermoelectric materials). In a case where a
material is calcined together with other materials, then an oxide
material like CaCoO/CaMnO is suitable. If p-type semiconductor layers 51
and n-type semiconductor layers 52 are prepared in a clayish green state
where raw material powder is kneaded together with a binder, a
plasticizer, or the like, and are calcined, then thermoelectric material
layers can be formed. It is preferable that this material is one together
with which insulating layers 53 can also be calcined.

[0084] As illustrated in FIG. 4B, a piezoelectric power generation section
(piezoelectric power generation module) PG is formed on top of the
thermoelectric power generation section TG illustrated in FIG. 4A. The
piezoelectric power generation section PG has a configuration such that
piezoelectric elements wherein electrodes 55 and 57 are formed on both
sides of piezoelectric material layers 53 are disposed in parallel at
intervals. in the piezoelectric power generation section PG, the
electrodes 55, which are located on the left surfaces of the
piezoelectric material layers, are connected to each other with a wire
W1, and the electrodes 57, which are located on the right surfaces of the
piezoelectric material layers, are connected to each other with a wire
W3. In a configuration wherein a single piezoelectric material layer is
held between a pair of electrodes 55 and 57, a unimorph type
piezoelectric element is formed. As will be mentioned later, if a central
electrode (inside conductive film) is disposed at the center of a
piezoelectric material layer, a bimorph type piezoelectric element is
formed. Materials such as lead zirconate titanate (PZT, Pb (Zr--Ti)
O3), lead lanthanum zirconate titanate (PLZT, (Pb--La) (Zr--Ti)
O3), Nb-added PZT, PNN-PZT
(Pb(Ni--Nb)O3--PbTiO3--PbZrO3), PMN-PZT (Pb(Mg--Nb)
O3--PbTiO3--PbZrO3), a perovskite oxide like barium
titanate, potassium niobate (KNbO3), aluminum nitride (AlN), lithium
niobate (LiNbO3), lithium titanate (LiTiO3), or zinc oxide
(ZnO) can be used as a piezoelectric material. A perovskite oxide is
suitable in a case where a piezoelectric material is integrally calcined
together with an oxide type thermoelectric conversion material.

[0085] A piezoelectric material is an insulator. By utilizing the
insulating properties of the pertinent piezoelectric material, it is
possible for insulating layers 53 of the thermoelectric power section TG
to be formed of thermoelectric material layers 53. Single layers are
caused to extend. Portions thereof, as they are, are used as insulating
layers 53. In other portions, electrodes are provided on both surfaces,
resulting in piezoelectric elements being able to be formed. The lower
ends of the piezoelectric elements are connected to the thermoelectric
power generation section TG, thereby forming fixed ends. Thermoelectric
material layers 51 and 52 are unnecessary in the thermoelectric power
generation section PG, and are removed, resulting in spaces (gap
portions) being formed, with the consequence that piezoelectric elements
are disposed at intervals. In such an arrangement where the arrangement
where piezoelectric material layers of the piezoelectric power generation
section PG and the insulating layers 53 of the thermoelectric power
generation section TG are caused to become common layers, and where the
thermoelectric material layers 51 and 52 of the thermoelectric power
generation section TG correspond to the gap portions of the piezoelectric
power generation section PG, it follows that the number of insulating
layers 53 of the thermoelectric elements corresponds to the number of
piezoelectric elements. In FIG. 4B, three pairs of n-type thermoelectric
elements are formed. Therefore, the number of insulating layers 53 is
five, and the number of piezoelectric element is five. It is possible to
arbitrarily change this number of elements.

[0086] No particular restrictions are imposed on the materials of
electrodes and wires, provided that the materials are insulators.
Different materials may be used for electrodes and wires. In a case where
electrodes and wires are integrally calcined together with an electrical
power generation device, it is preferable that the materials are capable
of withstanding integral calcination. For example, Platinum (Pt), nickel
(Ni), palladium (Pd), silver-palladium (Ag--Pd), etc. can be mentioned as
such materials. In this regard, surface electrodes (outside conductive
films) 55 and 57 can also be formed by plating, vapor deposition,
sputtering, CVD, or the like subsequent to ceramics calcination. In this
case, it is also possible to use metals such as iridium (Ir), chromium
(Cr), copper (Cu), titanium (Ti); nitrides such as titanium nitride;
carbides such as tungsten carbide (WC); and oxides such as indium tin
oxide (ITO). In order to enhance the thermal conductivity for the
thermoelectric elements, it is preferable that a material with high
thermal conductivity, such as copper or aluminum, is used so as to form
large thicknesses.

[0087] The upper ends of the piezoelectric elements form movable ends. A
weight 58 is connected to the movables ends of the piezoelectric elements
via a flexible adhesive layer 59. No particular restrictions are imposed
on the material of the weight 58 so long as it has mass. For example, the
weight 58 can be formed of a stainless plate. The adhesive layer 59 is
formed of elastic silicone resin, for example, and does not fix the
weight 58 to the piezoelectric material layers 53, but connects the
former to the latter in a state where connection angles can be changed.
It is possible for the piezoelectric material layers 53 of the
piezoelectric power generation section PG to be deformed arc-wise at an
approximately uniform curvature.

[0088] If the movable ends of the piezoelectric material layers 53 are
fixed to the weight 58, resulting in the connection angle being fixed to
90 degrees for example, then with the movement of the weight 58, the
upper side and the lower side of the piezoelectric material layers 53 are
bent in opposite directions (in an S-shape), with the result that
electric charges are generated in a way that the polarity on the upper
side and the polarity on the lower side are reverse to each other,
leading to the piezoelectric effect being offset.

[0089]FIG. 4C illustrates a case where the piezoelectric elements have a
bimorph structure. This structure is such that the piezoelectric material
layers 53 are each divided into two layers, which are piezoelectric
material layers 53a and 53b, and that these layers are bonded together
with a central electrode (inside conductive film) 56 therebetween.
Central electrodes 56 are connected to each other with a wire W2. The
wire W2, which connects the central electrodes 56, supplies the output of
the piezoelectric power generation section PG, together with a wire W1,
which mutually connects surface electrodes 55 on the outside of the
piezoelectric material layers, and with a wire W3, which mutually
connects surface electrodes 57. The piezoelectric material layers 53a and
the electrodes 55 and 56 on both sides form left piezoelectric elements,
and the piezoelectric material layers 53b and the electrodes 56 and 57 on
both sides form right piezoelectric elements. The left piezoelectric
elements and the right piezoelectric elements combined form bimorph type
piezoelectric elements. Similarly to FIG. 4B, a weight is connected to
the movable end to the piezoelectric power generation section with
flexible adhesive.

[0090] The deformation which occurs in the right piezoelectric element and
the deformation which occurs in the left piezoelectric element have
reverse properties, such as elongation and contraction. In the case of a
bimorph type piezoelectric element, it is preferable that spontaneous
polarizations are generated in piezoelectric material layers 53a and 53b.
A mode wherein polarizations are generated in the same direction and a
mode wherein polarizations are generated in opposite directions are
feasible. If the wires W1 and W3 are connected in common, and if a
voltage is applied between W2 and the common connection, then in the
piezoelectric material layers 53a and 53b, electric fields are generated
which are reverse in the thickness direction, and the piezoelectric
material layers 53a and 53b are polarized in opposite directions.
Piezoelectric material is a ferroelectric as well. Polarization remains
even after the applied voltage is removed. If, by being driven by the
weight 58, the bimorph type piezoelectric element vibrates and bends, one
of the piezoelectric material layers 53a and 53b elongates, and the other
contracts. Due to the piezoelectric transverse effect (d31 effect), the
generated voltage takes a value which corresponds to the acceleration of
the weight 58. The voltage generated between two surface electrodes 55
and 57 turns out to be equal to the sum (total added value) of the
voltage generated between both surfaces of the piezoelectric material
layer 53a and the voltage generated between both surfaces of the
piezoelectric material layer 53b.

[0091] If a voltage is applied between the wire W1 and the wire W2,
electric fields are applied to the left piezoelectric material layers
53a, resulting in polarizations being generated. In the next place, if a
similar voltage is applied between the wire W2 and the wire W3, electric
fields are applied to the right piezoelectric material layers 53b,
resulting in polarizations being generated in the same direction as
polarizations in the piezoelectric material layers 53a. In this case, the
voltages generated in two types of surface electrodes 55 and 57 have the
same polarity as for the central electrodes 56. If the electrodes 55 and
57 (wires W1 and W3) are jointly connected to one of the output
terminals, and if the electrodes 56 (wire W2) is connected to the other
output terminal, then the resulting voltage is 50 percent, compared to a
reverse-direction type. However, the resulting current is twice as high.
Therefore, there is no particular difference in terms of electric power.

[0092] In this regard, the surface electrodes 55 and 57 extend from the
upper part of the piezoelectric power generation section to the vicinity
of the upper ends of the thermoelectric material layers 51 and 52 of the
thermoelectric power generation section. Electrical conductors such as
metals have not only high electrical conductivity but also high thermal
conductivity. If the surface electrodes 55 and 57 are formed of copper,
aluminum, or the like, which has high thermal conductivity, and if the
thickness of these surface electrodes are made larger than that of the
center electrodes 56, which primarily function as electrical conductors,
then the surface electrodes 55 and 57 can be provided with not only
functions as electrical conductors but also functions as thermal
conductors, resulting in improved heat transfer characteristics.

[0093] By making reference to FIG. 5A to FIG. 5M, a more specific
explanation will be made of a method of the bimorph type
piezoelectric-thermoelectric power generation device based on Embodiment
2.

[0094] As illustrated in FIG. 5A, ceramic green which is prepared by
kneading together PZT-based piezoelectric ceramic powder, binder resin,
and a plasticizer, is molded, by using a doctor blade, into a ceramic
green sheet 63 which is approximately 50 μm thick and whose area is
equivalent to approximately 100 mm×100 mm. In this regard, for the
purpose of simplifying illustration, a portion where two
piezoelectric-thermoelectric power generation devices are disposed
opposite to each other is illustrated. In a subsequent process, the
ceramic green sheet 63 is divided at the center into the left portion and
the right portion, resulting in two electric power generation devices
being formed.

[0095] As illustrated in FIG. 5B, 50 μm diameter wiring via holes VH1
to VH4 are punched out by means of a punch. Via holes VH1 for
piezoelectric elements and via holes VH4 for thermoelectric elements are
illustrated as examples. The via holes for the thermoelectric elements
exist in the upper part or the lower part of the thermoelectric material
layers 51 and 52 (FIG. 4C). In FIG. 5B, via holes VH4 which are to be
disposed on top of thermoelectric material layers are illustrated as
examples. However, there are cases where via holes to be disposed in the
lower part of the thermoelectric material layers are formed at both ends
of the green sheet. Since each bimorph type thermoelectric element
includes three electrodes, via holes VH2 and VH3 for other electrodes are
also formed.

[0096] As illustrated in FIG. 5C, a bimorph type piezoelectric element has
surface electrodes 55 and 57 on both sides (vertical sides) of a central
electrode 56 with piezoelectric material layers in between. Connection
wirings can be formed by extending portions of electrodes outward and by
disposing via holes VH1, VH2, and VH3 in extension portions.

[0097] As illustrated in FIG. 5D, the via holes VH1 to VH4 (FIG. 5B) are
filled with Ag--Pd paste by means of screen printing, resulting in via
conductors VC1 to VC4 being formed. In this regard, neither via
conductors VC2 nor conductors VC3 appear in the cross-sectional view in
FIG. 5D.

[0098] As illustrated in FIG. 5E, by using Ag--Pd paste, an electrode
layer EL for the piezoelectric element is formed on the surface of the
green sheet 63 by means of screen printing. The electrode layer EL forms
one of the electrodes 55, 56, or 57. Here, the surface electrode 55 is
illustrated as being formed, for example.

[0099] As illustrated in FIG. 5F, by means of screen printing, the
following patterns are selectively formed on the green sheet 63, on which
the surface 55 electrode is formed: a pattern for piezoelectric material
(insulator) paste 63; a pattern for p-type semiconductor thermoelectric
material paste 61; a pattern for Ag--Pd paste, which is to be formed in a
wiring portion; and a pattern for resin paste RP, which is to be formed
in a portion that is to become a vacant space.

[0100]FIG. 5G illustrates a case where an n-type semiconductor
thermoelectric material paste 62 is disposed in place of the pattern for
p-type semiconductor thermoelectric material paste 61, and where
connection wires VC4 in an insulating layer 63 are formed at both ends.
It is possible to change wiring patterns through design.

[0101]FIG. 5H illustrates a state where a central electrode 56 is formed
on the lower surface of the configuration in FIG. 5F, where a
piezoelectric material layer green sheet 63 is laminated on the lower
surface of a piezoelectric material layer 63 by covering the central
electrode 56, and where a surface electrode 57 and a wire are formed. The
basic configuration of a bimorph type piezoelectric element is prepared.

[0102] FIG. 5I illustrates a state where a central electrode 56 is formed
on the lower surface of the configuration in FIG. 5G, where a
piezoelectric material layer green sheet 63 is laminated on the lower
surface of a piezoelectric material layer 63 by covering the central
electrode 56, and where a surface electrode 57 and a wire are formed.
Similarly to FIG. 5H, the basic configuration of a bimorph type
piezoelectric element is prepared. In this regard, it is also possible to
prepare a lamination configuration portion without forming a bimorph
structure in advance. It is possible to change lamination structure
fabrication processes in various ways.

[0103] As illustrated in FIG. 5J, a plurality of green sheets wherein a
configuration required for forming an electric power generation device is
formed, are aligned and laminated. The laminated structure is integrated
by means of hot pressing, resulting in a laminated body being formed.

[0104] As illustrated in FIG. 5K, the laminated body is degreased in the
atmosphere, and is calcined, resulting in a sintered body being obtained.
During this process, the resin paste RP is decomposed, scattered, or
burned, thereby disappearing. Vacant spaces VP remain in places which
used to be occupied by the resin paste RP. The vacant spaces form gaps
between piezoelectric elements.

[0105] As illustrated in FIG. 5L, the sintered body is cut off into
individual piezoelectric power generation devices. The height of the
electric power generation devices is in the range of 5 mm to 10 mm, for
example.

[0106]FIG. 5M illustrates a plan view. In FIG. 5M, the height (length in
FIG. 5L) of the electric power generation devices is in the range of 5 mm
to 10 mm, for example. In FIG. 5M, the lateral (lamination-wise)
dimension turns out to be a little less than 1 mm, provided that the
piezoelectric ceramic layers and the thermoelectric ceramic layers are
each 50 μm or so. Subsequently, as illustrated in FIG. 4B, the weight
58 is elastically connected to the top of the piezoelectric elements by
means of the adhesive layer 59. Thus a bimorph type
thermoelectric-piezoelectric power generation device is fabricated. In
this regard, when a unimorph type electric power device is to be
manufactured, what is to do is to omit unnecessary processes.

Embodiment 3

[0107]FIG. 6A illustrates a cross-sectional view of an electric power
generation device based on Embodiment 3. The electric power generation
device based on Embodiment 3, too, includes a thermoelectric power
generation module and a piezoelectric power generation module, similarly
to the electric power generation devices based on Embodiments 1 and 2.
The thermoelectric power generation module and the piezoelectric power
generation module connect thermally and mechanically to each other. The
piezoelectric power generation module includes piezoelectric members
wherein deformation occurs due to vibrations of the thermoelectric power
generation module.

[0108] An inside conductive film 71 is disposed between a pair of
piezoelectric material plates 70. One end (the lower end in FIG. 6A) of
the piezoelectric material plates 70 serves as a fixed end. The end (the
upper end in FIG. 6A) opposite to the fixed end serves as a movable end.
The inside conductive film 71 is exposed to the end face on the side of
the fixed end. At the movable end, the piezoelectric material plates 70
are continuous with each other.

[0109] Outside conductive films 72 and 73 are disposed, respectively, on
the outer surfaces of the pair of piezoelectric material plates 70. If a
comparison is made between the electric power generation device based on
Embodiment 3 and the piezoelectric element which is based on Embodiment 1
and is illustrated in FIG. 2, it follows that the piezoelectric material
plates 70, the inside conductive film 71, and the outside conductive
films 72 and 73, which are based on Embodiment 3, correspond,
respectively, to the piezoelectric material plates 42, the inside
conductive film 41, and the outside conductive films 44, which are shown
in FIG. 2. A bimorph type piezoelectric element is composed of the
piezoelectric material plates 70, the inside conductive film 71, and the
outside conductive films 72 and 73.

[0110] Electrodes 75 and 76 are mounted on the fixed ends of the outside
conductive films 72 and 73, respectively. The outside conductive films 72
and 73 are connected to each other by a conductive member 74 at the
movable end of the piezoelectric material plates 70. A weight 77 is
mounted on the movable end of the piezoelectric material plates 70. The
weight 77 is, for example, soldered to the conductive member 74.

[0111] As illustrated in FIG. 6B, if the movable end of the piezoelectric
material plates 70 undergoes displacement with respect to the fixed end,
strains are generated in the piezoelectric material plates 70. Due to
these strains, a voltage is generated between the outside conductive
films 72 and 73.

[0112] The explanation will be continued by returning to FIG. 6A. The
inside conductive film 71 and the outside conductive films 72 and 73 are
connected to an output terminal 82 via a diode bridge 80. The
electromotive force caused by the strains of the piezoelectric material
plates 70 are taken out to the outside via the output terminal 82.

[0113] The outside conductive film 72, which is one of the outside
conductive films, is formed of a p-type thermoelectric material, and the
outside conductive film 73, which is the other outside conductive film,
is formed of an n-type thermoelectric material. The electrode 75, the
outside conductive film 72, the conductive member 74, the outside
conductive film 73, and the electrode 76 form a n-type thermoelectric
element. If a temperature difference occurs between the fixed end and the
movable end, a voltage is generated between the electrode 75 and the
electrode 76. The electromotive force caused by thermoelectric conversion
is taken out to the outside via an output terminal 81 which is connected
to the electrodes 75 and 76.

[0114] For example, the materials that are the same as the piezoelectric
material and the thermoelectric material which are used in Embodiment 1
and Embodiment 2 can be used as a piezoelectric material and
thermoelectric a material, respectively.

[0115]FIG. 7A provides a side view of the electric power generation
device which is illustrated in FIG. 6A. The electrode 76 is connected to
the fixed end of the outside conductive film 73. The conductive member 74
is connected to the movable end. The weight 77 is mounted on the movable
end of the piezoelectric material plates with the conductive member
therebetween. A plurality of fins 77A are provided on the weight 77. In a
case where the fixed end is connected to a high temperature heat source,
a temperature difference occurs between the fixed end and the movable end
because heat is radiated from the fins 77A. Furthermore, the weight 77
amplifies the displacement of the movable end caused by the vibrations of
the fixed end of the piezoelectric material plates 70.

[0116]FIG. 7B illustrates a cross-sectional view of FIG. 7A through the
dashed-dotted line 7B-7B. The inside conductive film 71 is held between
the pair of piezoelectric material plates 70. The outside conductive film
72 is formed on the outer surface of one of the piezoelectric material
plates 70. The outside conductive film 73 is formed on the outer surface
of the other piezoelectric material plate 70. The inside conductive film
71 is exposed to the end faces on both sides of the piezoelectric
material plates 70. In this respect, it is not always necessary to expose
the inside conductive film 71.

[0117] In the electric power generation device based on Embodiment 3, the
outside conductive films 72 and 73 serve also as thermoelectric material
layers of thermoelectric elements. Consequently, it becomes possible to
take steps to miniaturize the electric power generation device.

Embodiment 4

[0118]FIG. 8 illustrates a cross-sectional view of an electric power
generation device based on Embodiment 4. The piezoelectric power
generation module of this electric power generation device of Embodiment
4 is equivalent to a configuration wherein three piezoelectric elements
which are based on Embodiment 3 and are typically illustrated in FIG. 6A
are connected in parallel. The thermoelectric conversion module is
equivalent to a configuration wherein three thermoelectric elements which
are based on Embodiment 3 and are typically illustrated in FIG. 6A are
connected in series.

[0119] A plurality of piezoelectric-thermoelectric elements 86 are
connected to an insulating base 85. The configuration of each of the
piezoelectric-thermoelectric elements 86 is the same as the configuration
of the electric power generation device illustrated in FIG. 6A. As
regards component parts of the piezoelectric-thermoelectric elements in
FIG. 8, the same reference symbols that are assigned to corresponding
component parts of the electric power generation device in FIG. 6A, are
assigned. The base 85 is formed of the same material as that of the
piezoelectric material plates 70. The connection portions between the
piezoelectric material plates 70 and the base 85 act as the fixed ends of
the piezoelectric-thermoelectric elements 86.

[0120] The electrode 76 of one of two mutually adjacent
piezoelectric-thermoelectric elements 86 and the electrode 75 of the
other adjacent piezoelectric-thermoelectric element 86 are formed of a
conductive member to be used in common. Consequently, those portions of
the piezoelectric-thermoelectric elements 86 which function as
thermoelectric elements are connected in series. The electrode 75 of the
piezoelectric-thermoelectric element 86 which is located at one end and
the electrode 76 of the piezoelectric-thermoelectric element 86 which is
located at other end are connected to the output terminal 81.

[0121] A conductive member 88 is embedded in the base 85. The conductive
member 88 not only mutually connects the inside conductive films 71 but
also is led out to the surface of the base 85. The outside conductive
films 72 and 73 of the piezoelectric-thermoelectric elements 86 are
mutually connected by the conductive members 74 on the movable end side
and by the conductive members which form the electrodes 75 and 76 on the
fixed end side. Consequently, those portions of the
piezoelectric-thermoelectric elements 86 which function as piezoelectric
elements are connected in parallel.

[0122] The electrodes 75, which are electrically connected to the outside
conductive films 72 and 73, and the conductive member 88, which is
embedded in the base 85, are connected to the output terminal 82 via a
diode bridge 80.

[0123] Weights 77 are mounted on the movable ends of all of the
piezoelectric-thermoelectric elements 86. Spacers 78 are disposed between
mutually adjacent weights 77. Flexible resin is used for the spacers 78.
The spacers 78 constrain the relative positions of the central points of
every two adjacent weights 77 so that the center-to-center distances of
the weights 77 will not change. However, the spacers 78 have the
flexibility to allow changes in the attitude of one of every two adjacent
weights 77 with respect the other weight 77.

[0124] For example, the base 85 is connected to a heat source on a high
temperature side, resulting in a temperature difference being created
between the fixed ends and the movable ends. For this reason,
thermoelectric power generation is performed. The piezoelectric material
plates 70 deforms due to the vibrations of the heat source, resulting in
piezoelectric power generation being performed.

[0125]FIG. 9 illustrates an equivalent circuit diagram of the electric
power generation device illustrated in FIG. 8. Each of the
piezoelectric-thermoelectric elements 86 is represented by a
four-terminal circuit which includes an direct current power supply Vt
and an internal resistor Rt, both of which are compatible with a
thermoelectric power generation function, and an alternating current
power supply Vp and a capacitor Cp, both of which are compatible with a
piezoelectric power generation function. Such four-terminal circuits are
cascade-connected. Direct current power supplies Vt are connected in
series, with the internal resistors Rt in between. Both ends of this
series circuit are connected to the output terminal 81 for a
thermoelectric function. A terminal pair of the four-terminal circuit in
the first stage is connected to the output terminal 82 for a
piezoelectric function via the diode bridge 80.

[0126] FIG. 10 illustrates a schematic view of a state where the
piezoelectric-thermoelectric elements 86 are deformed. Since the spacers
78 connect the weights 77, the center-to-cent distances Lc of the weights
77 do not change. Consequently, it is possible to prevent mutual
collision of the weights 77. Furthermore, in all
piezoelectric-thermoelectric elements 86, similar deformation occurs in
the piezoelectric material plates 70. The alternating current power
supplies Vp illustrated in FIG. 9 generate electric voltages of the same
phase. Therefore, power generated by piezoelectric effect can be
efficiently taken out to the outside.

[0127] Furthermore, the spacers 78 allow relative attitude changes of
mutually adjacent weights 77. Consequently, the piezoelectric material
plates 70 bend in a single direction in the whole regions extending from
the fixed ends to the movable ends. Since the bending direction does not
reverse, polarizations caused by the piezoelectric effect can be
prevented from being cancelled

[0128] FIG. 11 illustrates a cross-sectional view of an electric power
generation device based on a variant example of Embodiment 4. In the
following explanation, attention will be focused on the differences from
the electric power generation device which are based on Embodiment 4 and
are illustrated in FIG. 9 and FIG. 10, with explanations omitted
regarding the same configurations.

[0129] In Embodiment 4, a weight 77 is mounted on each of the
piezoelectric-thermoelectric elements 86. In the variant example, a
weight-to-be-used-in-common 77 is mounted on the movable ends of the
plurality of piezoelectric-thermoelectric elements 86 by means of a
flexible adhesive layer 90. Specifically, the adhesive layer 90 bonds the
weight 77 to conductive members 74.

[0130] FIG. 12 illustrates a cross-sectional view of
piezoelectric-thermoelectric elements 86 in a deformed state. The
adhesive layer 90 has the flexibility to allow changes in the attitudes
of the movable ends of the piezoelectric-thermoelectric elements 86 with
respect to the weight 77. Consequently, similarly to the case of
Embodiment 4, the piezoelectric-thermoelectric elements 86 bend in a
single direction in the whole regions extending from the fixed ends to
the movable ends.

[0131] In the next place, by making reference to FIG. 13A to FIG. 13P, an
explanation will be made of a method of manufacturing the electric power
generation device which is based on Embodiment 4 and is illustrated in
FIG. 8.

[0132] As illustrated in FIG. 13A, a green sheet 100 which includes
piezoelectric ceramic powder is formed. A method which is the same as the
method of forming the green sheet 63 is applied to the forming of the
green sheet 100, the second above-mentioned method being illustrated in
FIG. 5A. The thickness of the green sheet 100 is 50 μm, for example.
The planar shape is a square, and the dimensions are 100 mm×100 mm.
The green sheet 100 corresponds to a piezoelectric material plate 70 in
FIG. 8. FIG. 13A illustrates a portion which corresponds to two electric
power generation devices (FIG. 8) which are disposed, with the movable
end positions facing each other. In reality, a portion which corresponds
to three or more electric power generation devices extends in the lateral
direction in FIG. 13A.

[0133] As illustrated in FIG. 13B, A plurality of 50 μm diameter via
holes 101 are formed in the green sheet 100 by means of a punch. The via
holes 101 are formed at positions where the conductive member 88
illustrated in FIG. 8 is disposed in the base 85.

[0134] As illustrated in FIG. 13C, pieces of Ag--Pd conductive paste 102
are filled into the via holes 101.

[0135] As illustrated in FIG. 13D, Ag--Pd conductive paste is
screen-printed on one of the surfaces of the green sheet 100, resulting
in inside conductive patterns 103 being formed. The inside conductive
patterns 103 correspond to inside conductive patterns 71 (FIG. 8).

[0136] As illustrated in FIG. 13E, p-type thermoelectric material paste is
screen-printed on that surface of the green sheet 100 which is opposite
to the surface where the inside conductive patterns 103 are formed, with
the result that a p-type thermoelectric pattern 104 is formed. The p-type
thermoelectric pattern 104 corresponds to an outside conductive film 72
(FIG. 8) formed of p-type thermoelectric material.

[0137] As illustrated in FIG. 13F, paste containing piezoelectric ceramics
is screen-printed on the surfaces of those regions of the green sheet 100
which are outside the edges of the p-type thermoelectric pattern 104,
resulting in insulating patterns 105 being formed. Openings which are
aligned with via holes 101 are provided in the insulating patterns 105.
The insulating patterns 105 correspond to a portion of the base 85 (FIG.
8).

[0138] As illustrated in FIG. 13G, pieces of Ag--Pd conductive paste 106
are embedded in the openings in the insulating patterns 105 by means of
screen printing. The pieces of Ag--Pd conductive paste 106 correspond to
a portion of a conductive member 88 (FIG. 8).

[0139] As illustrated in FIG. 13H, resin paste is screen-printed on the
p-type thermoelectric pattern 104, resulting in a resin pattern 107 being
formed. The resin pattern 107 corresponds to a gap portion between
piezoelectric elements 86 illustrated in FIG. 8.

[0140] As illustrated in FIG. 13I, paste containing piezoelectric ceramics
is screen-printed on the insulating patterns 105, resulting in insulating
patterns 108 being formed. The insulating patterns 108 correspond to a
portion of the base 85 (FIG. 8). The insulating patterns 108 and the
resin pattern 107 are disposed with a gap therebetween. Furthermore,
openings that are aligned with the openings in the insulating patterns
105, which are located under the insulating patterns 108, are provided in
the insulating patterns 108.

[0141] As illustrated in FIG. 13J, Ag--Pd insulating paste is embedded
between the resin pattern 107 and the insulating patterns 108, and in the
openings provided in the insulating patterns 108, resulting in conductive
patterns 109 being formed. The conductive patterns 109 correspond to
electrodes 75 or 76 (FIG. 8) and a portion of the conductive member 88.

[0142] In the processes performed so far, a first laminated body 120 is
fabricated. The first laminated body 120 corresponds to the following
items in FIG. 8: an inside conductive film 71, piezoelectric material
plates 70, an outside conductive film 72, and a hollow portion outside
the outside conductive film 72.

[0143] As illustrated in FIG. 13K, a second laminated body 130 is
fabricated by a method similar to that for the first laminated body 120.
The second laminated body 130 corresponds to the following items in FIG.
8: piezoelectric material plates 70, an outside conductive film 73, and a
hollow portion outside the outside conductive film 73. A resin pattern is
disposed in the hollow portion.

[0144] As illustrated in FIG. 13L, first laminated bodies 120 and second
laminated bodies 130 are alternately stacked up. At this time, the green
sheet, which corresponds to a piezoelectric material plate 70, of each of
the second laminated bodies 130 is brought into close contact with the
inside conductive patterns 103 of the pertinent first laminated body 120.
Furthermore, the resin pattern of each of the first laminated bodies 120
is brought into close contact with the resin pattern of the pertinent
second laminated body 130.

[0145] At least one conductive pattern 103 extends to the end face of a
green sheet. Furthermore, via holes which correspond to the via holes
illustrated in FIG. 13C are not formed in the insulating patterns 108 of
the first laminated body 120 which is disposed in the most outward
position. Similarly, no via holes are formed in the corresponding
insulating patterns of the second laminated body 130 which is disposed in
the most outward position. Hot pressing is performed, with the laminated
bodies stacked up.

[0146] As illustrated in FIG. 13M, degreasing is performed in the
atmosphere, and subsequently, calcination is performed. During this
process, the resin patterns are decomposed, scattered, or burned, thereby
disappearing. Vacant spaces 135 are formed in the portions where the
resin patterns used to be disposed. Pieces of Ag--Pd conductive paste
102, inside conductive patterns 103, and conductive patterns 109, etc.
are calcined, resulting in inside conductive films 71, electrodes 75 and
76, and conductive members 88 being formed. Green sheets 100 etc. are
calcined, resulting in piezoelectric material plates 70 being formed.
Furthermore, items such as insulating patterns 105 and 108 are calcined,
resulting in a base 85 being formed.

[0147] As illustrated in FIG. 13N, the resulting sintered body is cut off
with a dicing saw or the like, thereby being divided into individual
electric power generation devices. The height H of an electric power
generation device is approximately 1 mm. The stack-wise dimension
(thickness) T is approximately 10 mm. The dimension (width) perpendicular
to the plane of paper on which FIG. 13N is drawn, is approximately 10 mm.
The lamination-wise repetition period is approximately 200 μm. The
lamination-wise repeat cycle length is approximately 200 μm.

[0148] As illustrated in FIG. 13O, conductive members 74 are formed at the
tips of piezoelectric material plates 70 and outside conductive films 72
and 73, resulting in outside conductive films 72 and 73 being
electrically connected to each other. It is possible to form the
conductive members 74, for example, by first screen-printing Ag--Pd paste
and by subsequently performing calcination.

[0149] FIG. 13P illustrates a cross-sectional view of FIG. 13O through the
dashed-dotted line 13P-13P. Conductive members 88 are embedded in the
base 85. The conductive members 88 are disposed at positions which
correspond to via holes 101 illustrated in FIG. 13B. In the last place,
weights 77 illustrated in FIG. 8 are mounted.

Embodiment 5

[0150] By making reference to FIG. 14A to FIG. 14F, an explanation will be
made of a method of manufacturing an electric power generation device
based on Embodiment 5. In the following explanation, attention will be
focused on the differences from the manufacturing method illustrated in
FIG. 13A to FIG. 13P, with explanations omitted regarding the same
configurations.

[0151] As illustrated in FIG. 14A, a plurality of via holes 101 and a
plurality of via holes 140 in a green sheet 100. FIG. 14B illustrates a
cross-sectional view of FIG. 14A through the dashed-dotted line 14B-14B.
The green sheet 100 is the same as the green sheet 100 illustrated in
FIG. 13A. In Embodiment 5, the via holes 140 are formed in addition to
via holes 101. The via holes 140 are discretely disposed at positions
which correspond to the tips of the piezoelectric elements 86 illustrated
in FIG. 8.

[0152] FIG. 14C illustrates a cross-sectional view of the electric power
generation device in the same stage as the stage illustrated in FIG. 13L.
Pieces of conductive paste 141 are filled in the via holes 140.

[0153] FIG. 14D illustrates a cross-sectional view of the electric power
generation device in the same stage as the stage illustrated in FIG. 13M.
Pieces of conductive paste 141 are calcined, resulting in conductive
members 74 being formed.

[0154] As illustrated in FIG. 14E, the resulting sintered body is cut off
with a dicing saw or the like. At this point in time, the conductive
members 74, which connect outside conductive films 72 and 73 to each
other, are already formed. Consequently, the screen-printing process
illustrated in FIG. 13O is not required.

[0155] FIG. 14F illustrates a cross-sectional view of FIG. 14E through the
dashed-dotted line 14F-14F. In the example illustrated in FIG. 13O, the
conductive members 74 covers the entire regions of the movable ends
(tips) of the piezoelectric-thermoelectric elements 86. However, in
Embodiment 5, the conductive members 74 are discretely distributed in the
width direction.

[0156] In Embodiment 5, the conductive members 74 at the tips of the
piezoelectric-thermoelectric elements 86 are formed at the same time as
the electrodes 75 and 76 and the inside conductive films 71 on the fixed
end side and as the conductive members 88 in the base 85. Consequently,
it is possible to reduce the number of manufacturing processes, compared
to the manufacturing method illustrated in FIG. 13A to FIG. 13P.

[0157] All examples and conditional language recited herein are intended
for pedagogical purposes to aid the reader in understanding the invention
and the concepts contributed by the inventor to furthering the art, and
are to be construed as being without limitation to such specifically
recited examples and conditions, nor does the organization of such
examples in the specification relate to a showing of the superiority and
inferiority of the invention. Although the embodiments of the present
invention have been described in detail, it should be understood that the
various changes, substitutions, and alterations could be made hereto
without departing from the spirit and scope of the invention.

Patent applications by Kazuaki Kurihara, Kawasaki JP

Patent applications by Kazunori Yamanaka, Kawasaki JP

Patent applications by Masaharu Hida, Kawasaki JP

Patent applications by FUJITSU LIMITED

Patent applications in class Having housing, mounting or support

Patent applications in all subclasses Having housing, mounting or support